// Copyright (c) 2004-2008 MySQL AB, 2008-2009 Sun Microsystems, Inc.
//
// MySQL Connector/NET is licensed under the terms of the GPLv2
// <http://www.gnu.org/licenses/old-licenses/gpl-2.0.html>, like most 
// MySQL Connectors. There are special exceptions to the terms and 
// conditions of the GPLv2 as it is applied to this software, see the 
// FLOSS License Exception
// <http://www.mysql.com/about/legal/licensing/foss-exception.html>.
//
// This program is free software; you can redistribute it and/or modify 
// it under the terms of the GNU General Public License as published 
// by the Free Software Foundation; version 2 of the License.
//
// This program is distributed in the hope that it will be useful, but 
// WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
// or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 
// for more details.
//
// You should have received a copy of the GNU General Public License along 
// with this program; if not, write to the Free Software Foundation, Inc., 
// 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA

using System.Collections;
using System.Diagnostics;
using System.Collections.Generic;
using System.Threading;
using MySql.Data.MySqlClient.Properties;

namespace MySql.Data.MySqlClient
{


    /// <summary>
    /// Summary description for MySqlPoolManager.
    /// </summary>
    internal class MySqlPoolManager
    {
        private static Hashtable pools = new Hashtable();
        private static List<MySqlPool> clearingPools = new List<MySqlPool>();

        // Timeout in seconds, after which an unused (idle) connection 
        // should be closed.
        static internal int maxConnectionIdleTime = 180;


        private static Timer timer = new Timer(new TimerCallback(CleanIdleConnections),
            null, maxConnectionIdleTime*1000, maxConnectionIdleTime*1000);

        private static string GetKey(MySqlConnectionStringBuilder settings)
        {
            string key  = settings.ConnectionString;
#if !CF
            if(settings.IntegratedSecurity && !settings.ConnectionReset)
            {
                try
                {
                    // Append SID to the connection string to generate a key
                    // With Integrated security different Windows users with the same
                    // connection string may be mapped to different MySQL accounts.
                    System.Security.Principal.WindowsIdentity id =
                        System.Security.Principal.WindowsIdentity.GetCurrent();

                    key += ";" + id.User;
                }
                catch (System.Security.SecurityException ex)
                {
                    // Documentation for WindowsIdentity.GetCurrent() states 
                    // SecurityException can be thrown. In this case the 
                    // connection can only be pooled if reset is done.
                    throw new MySqlException(Resources.NoWindowsIdentity, ex );
                }
            }
#endif
            return key;
        }
        public static MySqlPool GetPool(MySqlConnectionStringBuilder settings)
        {
            string text = GetKey(settings);

            lock (pools.SyncRoot)
            {
                MySqlPool pool = (pools[text] as MySqlPool);

                if (pool == null)
                {
                    pool = new MySqlPool(settings);
                    pools.Add(text, pool);
                }
                else
                    pool.Settings = settings;

                return pool;
            }
        }

        public static void RemoveConnection(Driver driver)
        {
            Debug.Assert(driver != null);

			MySqlPool pool = driver.Pool;
			if (pool == null) return;

            pool.RemoveConnection(driver);
        }

        public static void ReleaseConnection(Driver driver)
        {
            Debug.Assert(driver != null);

			MySqlPool pool = driver.Pool;
			if (pool == null) return;
			
            pool.ReleaseConnection(driver);
        }

        public static void ClearPool(MySqlConnectionStringBuilder settings)
        {
            Debug.Assert(settings != null);
            string text;
            try
            {
                text = GetKey(settings);
            }
            catch (MySqlException)
            {
                // Cannot retrieve windows identity for IntegratedSecurity=true
                // This can be ignored.
                return;
            }
            ClearPoolByText(text);
        }

        private static void ClearPoolByText(string key)
        {
            lock (pools.SyncRoot)
            {
                // if pools doesn't have it, then this pool must already have been cleared
                if (!pools.ContainsKey(key)) return;

                // add the pool to our list of pools being cleared
                MySqlPool pool = (pools[key] as MySqlPool);
                clearingPools.Add(pool);

                // now tell the pool to clear itself
                pool.Clear();

                // and then remove the pool from the active pools list
                pools.Remove(key);
            }
        }

		public static void ClearAllPools()
		{
			lock (pools.SyncRoot)
			{
				// Create separate keys list.
				List<string> keys = new	List<string>(pools.Count);

				foreach (string key in pools.Keys)
					keys.Add(key);

				// Remove all pools by key.
				foreach (string key in keys)
					ClearPoolByText(key);
			}
		}

        public static void RemoveClearedPool(MySqlPool pool)
        {
            Debug.Assert(clearingPools.Contains(pool));
            clearingPools.Remove(pool);
        }

        /// <summary>
        /// Remove drivers that have been idle for too long.
        /// </summary>
        public static void CleanIdleConnections(object obj)
        {
            List<Driver> oldDrivers = new List<Driver>();
            lock (pools.SyncRoot)
            {
                foreach (string key in pools.Keys)
                {
                    MySqlPool pool = (pools[key] as MySqlPool);
                    oldDrivers.AddRange(pool.RemoveOldIdleConnections());
                }
            }
            foreach(Driver driver in oldDrivers)
            {
                driver.Close();
            }
        }
    }
}